In Missouri, the parent who receives child support has a responsibility to notify the other parent when a child becomes emancipated.
Having just read that, you might think "well, who cares? If I can get my child's father to pay for a few more months, it will be a good thing. And besides, what's he going to do about it?"
Well, slow down. He has statutory remedies.
If you, as a parent receiving child support, decide to not let the other parent know when an event that terminates child support has occurred, you become liable to the other parent to repay him the amount of the child support that he shouldn't have had to pay. If there is another child in your family, that means that the child support amount will be adjusted back to the date of emancipation and the paying parent will be entitled to receive a credit.
So - think about this scenario. Your oldest child just graduated from high school and ran off and got married or joined the military or started working full time. Aha, you think, I can use the extra child support for the baby (who is, by now, 13 or 14 years old). So you don't tell the paying parent that he's no longer liable to support the older child.
A few months later, the paying parent finally figures out that the older child is emancipated and files a motion with the court to have that child declared emancipated and have the child support readjusted to reflect just one child. Aha, you figure - all I have to do is duck service and I can keep on receiving the child support for 2 children even though I'm only eligible to receive child support for one child.
That's what we call a bad thought - and an expensive one at that.
What really happens is that you are just delaying the inevitable. The older child is still emancipated (and just because you duck service for a while doesn't change that). When the service is completed, you will have more months for which you will owe the paying parent a refund.
Usually the courts will let you have the refund amount taken as a reduction in the child support you would otherwise receive for the remaining child, and then spread that over a period of months - or, sometimes, even years (depending on the age of the younger child).
So, if you had been receiving $500.00 for both of the children and the child support for just one child is $350.00, here's how it can play out: The older child becomes emancipated and you don't get served with a motion to terminate child support for 6 months. 6 times 150 is $900.00. So you owe the paying parent $900.00. Either you or your lawyer must then negotiate how that money gets paid out. And, if you delay the reduction to child support for just one child past the 6 months in my example, the amount of the difference (whatever number that might be) just keeps on increasing the amount you owe the other parent.